| 摘要 |
PURPOSE:To make the efficiency of exhaust gas control securable even using an inexpensive carburetor, by enlarging the suction pressure to be imposed on an air feed part by degrees in proportion to the increase of a suction air quantity. CONSTITUTION:In proportion to enlargement in the opening of a throttle valve 11, that is, in proportion to the increase of a suction air quantity, the suction pressure to be imposed on an air port 40 grows larger so that an air quantity to be fed from the air feed port 40 becomes increased. The variation range of an air-fuel ratio on the basis of the action of air feeding from the air feed port 40 comes constant irrespective of the suction air quantity. In opening or closing a solenoid valve 50, the opening area of the solenoid valve 50 is set so as to cause the variation range of the air-fuel ratio to be fed inside an engine cylinder to be periodically varied between somewhere around + or -0.2-+ or -1.0 to a theoretical air- fuel ratio. |
